<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      "use strict";
      function Person(x, y) {
        // let this=undefind;
        // this = {} new 对this重新赋值
        console.log(x + y, this);
        // return undefined 默认返回
        // return this new 修改改了函数返回值
      }

      console.log(Person(1, 2)); // this=window
      console.log(new Person(2, 3)); // this={}
    </script>
  </body>
</html>
